1. Field of the Invention
The present invention relates to a parts feeder dispensing chip-shaped electronic parts.
2. Background Art
Japanese unexamined Laid-open patent publication SH0.60-24100 discloses a parts feeder, comprising a feed table having an upper surface and moving horizontally, a plurality of parts feed units arranged on the upper surface of the feed table, each of the parts feed units including a carrying tape carrying parts arranged on one surface of the carrying tape, a cover tape attached to the one surface of the carrying tape and covering the parts, means for peeling the cover tape from the carrying tape, means for dispensing the carrying tape and the cover tape at a position of a dispensation of the parts in the part feed unit while the peeling means peels the cover tape from the carrying tape, and a shutter shutting a space above the position of the dispensation of the parts to prevent the parts from escaping from the position of the dispensation of the parts, the parts feeder comprising a sucker sucking the parts at a position of a suction of the parts via the position of the dispensation of the parts in a parts feed unit positioned at the position of the suction of the parts by the feed table. In this prior art parts feeder, a shutter operates in interlock with the operation of a ratchet of a tape dispensing means. That is, when the tape is dispensed, the shutter covers a part being delivered to a position of a dispensation of the parts. On the other hand, the shutter is moved in interlock with a return of the ratchet when the parts have been positioned, to open a space above the position of the dispensation of the parts to allow the tubular sucker to suck the part. The shutter is in the open position until a next feed of the tape after the tape has been dispensed, to uncover the space above the position of the dispensation of the parts. Therefore, if the prior art parts feeder has the so-called feedforward control system of dispensing the parts at a position other than a position of the suction of the parts at which the sucker picks up the parts, in order to increase the speed of the parts feeder, the parts which have been delivered to the position at which the parts are fed may be uncovered and escape while the parts feed unit travels from that position to the position of the suction of the parts.
In order to eliminate this drawback, Japanese unexamined patent application publication SH0.61-64199 discloses a technique by which an action against the force of a tension spring of a feed lever of a parts feed unit opens a shutter to allow a chuck to take out a part, a push by the kicker is released, and the tension spring returns the feed lever to operate the shutter and feed a tape. In this case, since the tension spring applies its force directly to the tape, which impacts the tape and may break sprocket holes in the tape, and the inertia of a tape feed mechanism may fail to stop the tape at a required position and to disorder the feed of the tape if a Z-table constituting a feed table moves before the kicker removes from the feed lever in order to increase the speed of the parts feeder, the parts feeder is designed so that the kicker regulates a return of the feed lever and subsequently removes from the feed lever and the Z-table subsequently moves.
However, in the parts feeder in which the kicker removes from the feed lever and then the Z-table moves, the stay time of the feed table must be shortened, the return speed of the feed lever must be accelerated and an acceleration of the feed speed of the tape must be increased for accelerating the speed of the parts feeder. The acceleration of the feed speed of the tape may break the sprocket holes in the tape and the inertia of the tape feed mechanism may fail to stop the tape at the required position, so that the tape feed of the parts feeder is unstable. Thus, this structure is inadequate to the acceleration of the speed of the parts feeder.